Molecular-level computational investigation of shock-wave mitigation capability of polyurea

Grujičić, M.; Yavari, R.; Snipes, J. S.; Ramaswami, S.; Runt, James; Tarter, J.; Dillon, Gregory P.

doi:10.1007/s10853-012-6716-4

Cited by 61 publications

(43 citation statements)

References 23 publications

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“…However, strain-induced crystallization of hard-domains is still possible considering the fact that hard-domains are often found to re-orient themselves, under loading, in the principal direction of deformation (morphological texture). This re-orientation has been found, in our molecular-level simulation work (Grujicic et al, 2012c), to be accompanied by additional internal reordering/crystallization of the hard-domains. Experimental evidence for this strain-induced hard-domain crystallization has been offered by Sheth et al (2004).…”

Section: Parameterization and Implementation Of The Modelsupporting

confidence: 68%

“…By combining the computational results presented by Grujicic et al (2012c) and the experimental findings reported by Runt and co-workers (Castagna et al, 2012), functional relationships are established between the hydrostatic material-model parameters, on the one hand, and the soft-segment molecular weight and curing temperatures on the other. These functional relations are shown using contour plots in Figure 7(a)-(c), respectively.…”

Section: Parameterization and Implementation Of The Modelmentioning

confidence: 95%

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Molecular- and domain-level microstructure-dependent material model for nano-segregated polyurea

Grujičić¹,

Snipes²,

Ramaswami³

et al. 2013

Multi Modelg in Mat & Struct

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Purpose -Polyurea is an elastomeric two-phase co-polymer consisting of nanometer-sized discrete hard (i.e. high glass transition temperature) domains distributed randomly within a soft (i.e. low glass transition temperature) matrix. A number of experimental investigations reported in the open literature clearly demonstrated that the use of polyurea external coatings and/or internal linings can significantly increase blast survivability and ballistic penetration resistance of target structures, such as vehicles, buildings and field/laboratory test-plates. When designing blast/ballistic-threat survivable polyurea-coated structures, advanced computational methods and tools are being increasingly utilized. A critical aspect of this computational approach is the availability of physically based, high-fidelity polyurea material models. The paper aims to discuss these issues. Design/methodology/approach -In the present work, an attempt is made to develop a material model for polyurea which will include the effects of soft-matrix chain-segment molecular weight and the extent and morphology of hard-domain nano-segregation. Since these aspects of polyurea microstructure can be controlled through the selection of polyurea chemistry and synthesis conditions, and the present material model enables the prediction of polyurea blast-mitigation capacity and ballistic resistance, the model offers the potential for the "material-by-design" approach. Findings -The model is validated by comparing its predictions with the corresponding experimental data. Originality/value -The work clearly demonstrated that, in order to maximize shock-mitigation effects offered by polyurea, chemistry and processing/synthesis route of this material should be optimized.

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Section: Parameterization and Implementation Of The Modelsupporting

confidence: 68%

Section: Parameterization and Implementation Of The Modelmentioning

confidence: 95%

Molecular- and domain-level microstructure-dependent material model for nano-segregated polyurea

Grujičić¹,

Snipes²,

Ramaswami³

et al. 2013

Multi Modelg in Mat & Struct

View full text Add to dashboard Cite

show abstract

“…6 for the homogenous PU coating and the laminate, both at a nominal strain rate of 2000 s −1 . This rate is at least two orders of magnitude slower than necessary to induce a transition to the glassy state [36], so although the polymer exhibits a high degree of viscoelasticity, it remains a rubber. As can be seen, the laminate is roughly 1.5 times stiffer than the polyurea, corresponding to a proportionally greater strain energy.…”

Section: Split Hopkinson Pressure Bar Testsmentioning

confidence: 99%

“…The work evolved from earlier studies on bilayers consisting of steel with a thin elastomer coating [33,34,35,36,37], the unique feature therein the large contribution of viscoelasticity to the absorption of impact energy. The particular polymers employed have segmental dynamics occurring on the time scale of the ballistic impact (ca.…”

Section: Introductionmentioning

confidence: 99%

Elastomer-metal laminate armor

et al. 2016

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• Polymer-aluminum laminates on the strike-face of steel plates enhance ballistic performance.• With judicious selection of substrate and laminate, a broad range of performance and weight combinations can be obtained.• There is both a reduction in magnitude of the substrate deformation and spatial dispersion of the impact.• The main function of the metallic layers is to stiffen the polymer without affecting the latter's viscoelasticity response. A study was carried out of pressure wave transmission and the ballistic penetration of steel substrates incorporating a front-face laminate, the latter consisting of alternating layers of thin metal and a soft polymer; the latter undergoes a viscoelastic phase transition on impact. The ballistic properties of laminate/steel structures are substantially better than conventional military armor. This enhanced performance has three origins: large energy absorption by the viscoelastic polymer, a significant strain-hardening of the material, and lateral spreading of the impact force. These mechanisms, active only at high strain rates, depend on the chemical structure of the polymer but not on the particular metal used in the laminate. G R A P H I C A L A B S T R A C T a b s t r a c t a r t i c l e i n f oPublished by Elsevier Ltd.

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“…The presence of dipoles along with (i) the lone electron pairs on the oxygen atoms; (ii) close proximity of the oxygen and hydrogen atoms of neighboring parallel PPTA molecules within the same sheet; and (iii) the operation of London-dispersion forces typically results in the formation of (strong) hydrogen bonds. London-dispersion forces are temporary intermolecular forces which are caused by instantaneous polarization of the interacting molecules due to repulsion of their adjacent electrons [1]. Within the hydrogen bonds, the N-H species acts as a bond donor, while O acts as a bond acceptor.…”

Section: Ppta Sheetsmentioning

confidence: 99%

The effect of plain-weaving on the mechanical properties of warp and weft p-phenylene terephthalamide (PPTA) fibers/yarns

et al. 2014

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Coarse-grained molecular statics/dynamics methods are first used to investigate degradation in the PPTA fiber/yarn tensile strength, as a result of the prior compressive or tensile loading. PPTA fibers/yarns experience this type of loading in the course of a plain-weaving process, the process which is used in the fabrication of ballistic fabric and flexible armor. The more common allatom molecular simulations were not used to assess strength degradation for two reasons: (a) the size of the associated computational domain rendering reasonable run-times would be too small and (b) modeling of the mechanical response of multi-fibril PPTA fibers could not be carried out (again due to the limited size of the computational domain). However, all-atom simulations were used to (a) define the coarse-grained particles (referred to as ''beads'') and (b) parameterize various components of the bead/bead force-field functions. In the second portion of the work, a simplified finite-element analysis of the plain-weaving process is carried out in order to assess the extent of tensile-strength degradation in warp and weft yarns during the weaving process. In this analysis, a new material model is used for the PPTA fibers/yarns. Specifically, PPTA is considered to be a linearly elastic, transversely isotropic material with degradable longitudinal-tensile strength and the longitudinal Young's modulus. Equations governing damage and strength/stiffness degradation in this material model are derived and parameterized using the coarse-grained simulation results. Lastly, the finite-element results are compared with their experimental counterparts, yielding a decent agreement.

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Molecular-level computational investigation of shock-wave mitigation capability of polyurea

Cited by 61 publications

References 23 publications

Molecular- and domain-level microstructure-dependent material model for nano-segregated polyurea

Molecular- and domain-level microstructure-dependent material model for nano-segregated polyurea

Elastomer-metal laminate armor

The effect of plain-weaving on the mechanical properties of warp and weft p-phenylene terephthalamide (PPTA) fibers/yarns

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